There is a widely known method of creating building structures in water wherein a preset area of a water basin is filled with some inert material to exceed the water level and then a building structure is erected on the surface of the formed island used as a base.
However, this method is highly labour-consuming and not economical enough since it requires great quantities of inert material and loading the material on floating facilities and delivering it to a building site.
In addition, this method requires the creation of special consolidation to impede landslide and wash-out of the material as well as its sliding down below the water level.
There is a known method of creating building structures in water (U.S. Pat. No. 4,511,288), wherein ballastable modules are floated to a preset area of a water basin, then they are submerged in turn, each module is placed on top of a preceding one. Then a structure is erected on a module projecting from water, this module used as a base.
The main drawback of such method is the impossibility of using it for erecting stationary, large-sized heavy structures. This is determined by the fact that hollow ballastable modules can neither be used as a foundation for such a structure, nor carry such a foundation. Therefore in practice this method is only used for creating temporary structures intended, for example, for locating drilling rigs, platforms, for receiving aircraft and for locating other structures of this sort.
In addition, this method is not economical enough since it requires the use of great quantities of excessive metal (material of ballastable modules) which is of no direct relation to the structure being created.
Another drawback is the necessity of connecting the modules with one another under water which complicates the method significantly.
And, finally, availability of several modules placed one on top the other affects significantly the reliability of the structure when erected at seismically dangerous areas, at water area subject to heavy sea-ways and also in cases when subsidence of the sea floor is possible.
There is a known method of creating building structures in water (EP No. 0199690) wherein a pontoon is floated to a preset area of the water basin, the pontoon height exceeding the water depth in this area. Then the pontoon is submerged and its upper (projecting from water) surface can be used as a base for erecting the structure.
Reliability of such a structure in contrast to the one created by the preceding method is considerably higher and, besides, is free of the drawbacks connected with the necessity of implementing under-water work on connecting the modules with each other. However all other drawbacks still exist.
There is a known method of creating building structures in water (EP No. 0800600) wherein a pan-shaped block is floated to a preset area of the water basin, this block consisting of a bottom, a deck located above the bottom, and walls hermetically embracing the bottom around its perimeter. Then the block is submerged onto the basin floor by way of filling it with water. The distance between the deck and block bottom is so selected that after the block is submerged onto the bottom, the deck remains above the water level. Then the structure is erected on the deck used as a base.
This method, as well as the two preceding ones, cannot be used for creating stationary, large-sized heavy structures since the deck itself can neither be used as a foundation for such structures, nor carry such a foundation.
In addition, this method is not economical enough since it requires the use of great quantities of excessive material (under-water portion of the pan-shaped block) which is of no direct relation to the structure being created.
There is a known method of creating a building structure wherein piles are first driven into the sea floor. Then a foundation is installed on the piles, and after that the structure is erected.
A drawback of this method is its high labour consumption and low economic efficiency determined by necessity of creating a foundation and erecting all the members of the structure in this case the work is implemented from floating facilities, often under water.